This invention relates to optical dermatology and more particularly to methods and apparatus for detecting skin contact with an optical radiation handpiece.
Where lasers or other optical radiation sources, such as flashlamps, are utilized to perform a dermatological procedure, it is important, for many such procedures, that good physical, optical and/or thermal contact be made and maintained between a handpiece delivering the optical radiation and the patient""s skin. Such contact accomplishes at least three things. First, since a controlled amount of radiant energy is delivered for a selected time period for most dermatological procedures in order to achieve the desired result, if there is not good optical contact with the skin, the applied radiation will not be efficiently optically coupled to the skin and the patient will therefore receive less radiation than intended. This may negatively impact the efficacy of the treatment. Second, since radiation applied to the dermis or below must pass through the epidermis, there is a danger of epidermal damage for many optical dermatology treatments. The damage threshold for epidermal damage may be raised by cooling the epidermis, preferably both before and during treatment. This is frequently done by cooling a handpiece in contact with the patient""s skin through which the optical radiation is applied, good thermal contact between the handpiece and the patient""s skin being required for such contact cooling to be effective. Therefore, the protocol for such treatments generally requires that the laser or other optical source not be fired until good contact between the handpiece and the skin has been established for a selected minimum time interval. Third, particularly where a laser is used, the radiation source may cause damage to eyes or other parts of the body if unintentionally fired when not in contact with the patients skin.
Therefore, for at least one of the above reasons, and frequently for two or more of these reasons, good contact with the patient""s skin is generally a required condition for permitting firing of the radiation source in an optical dermatology procedure. While a number of procedures have been utilized in the past for detecting contact with the patient""s skin, many such procedures have been complicated, expensive, and have not always been effective. Further, some of these procedures have not only permitted firing when there is contact, but have also permitted firing when there is some fault in the system. However, since firing only when there is good contact is a safety issue, this is generally not acceptable, it being required that the laser or other light source only fire when there is good contact and under no other condition, the default condition of the system being that the source is not firing. A need therefore exists for improved methods and apparatus for contact detection between a handpiece used in an optical dermatology system and a patient""s skin which overcome the various deficiencies indicated above.
In accordance with the above, this invention, in accordance with one aspect thereof, provides apparatus for use in a system for utilizing optical radiation applied through a handpiece in contact with a patient""s skin to perform a dermatological treatment on the patient, the apparatus assuring good contact between the handpiece and the patient""s skin when radiation is applied. The apparatus includes a detector for picking up at least selected light at a skin-contacting surface of the handpiece and a control which enables application of the radiation only when light detected by the detector is within a selected range. The detector may be in the handpiece or may be in a console connected to the handpiece through an umbilical, an optical fiber being provided in the latter instance in the umbilical for transmitting light from the interior of the handpiece to the detector. A notch filter may be positioned to prevent radiation at the selected wavelength of an optical radiation source from reaching the detector, the selected light being at a wavelength other than the selected wavelength. The selected light may be ambient light or a source of the selected light may be provided which is positioned so that light from the source enters the handpiece when the handpiece is not in contact with the patient""s skin but is substantially blocked from entering the handpiece when the handpiece is in good contact with the patient""s skin. The light source may be at a wavelength or at a wavelength band other than that of the optical radiation and a filter may be provided which blocks all radiation from being applied to the detector other than radiation at the wavelength or wavelength band of the source. The handpiece is preferably designed to substantially prevent all of the selected light from entering the handpiece when the handpiece is in good contact with the patient""s skin. The control may enable application of radiation only when the light detected by the detector is below a selected threshold, but preferably enables application of radiation when the light detected by the detector is both below a selected first threshold and above a second much lower threshold.
In accordance with another aspect of the invention, a method is provided for assuring good contact between a handpiece and a patient""s skin before radiation is applied, the method being utilized in an optical radiation system of the type indicated above and including enabling application of the radiation only when selected light detected in the handpiece is within a selected range. More specifically, the method includes thresholding said detected light, and utilizing the results of the thresholding to control the application of radiation. The applying of the selected light to the handpiece is preferably done in a manner such that light enters the handpiece when the handpiece is not in contact with the patient""s skin but is substantially blocked from entering the handpiece when the handpiece is in good contact with the patient""s skin. More particularly, the selected light applied to the handpiece is preferably from a source of a wavelength or wavelength band other than that of the optical radiation and all radiation other than the radiation at the wavelength or wavelength band of the selected light is filtered, the filtered radiation being applied to a detector which generates an output when the radiation is within the selected range. The control preferably enables application of radiation only when the selected light detected in said handpiece is both below a selected first threshold and above a second much lower threshold.
In accordance with still another aspect of the invention, apparatus is provided for protecting the patient in a system of the type indicated above which apparatus includes a mechanism for assuring that radiation from the source is not normally applied to the handpiece, a mechanism for detecting when it is safe to apply radiation from the source to the handpiece and a mechanism which is operative in response to the detecting mechanism for enabling application of radiation from the source to the handpiece.
The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of a preferred embodiment of the invention as illustrated in the accompanying drawing.